The Electronics Industry Association (EIA) has provided standards for electrical, mechanical and functional interfaces between terminals, teletypes, CRTs, PCs and other types of data terminal equipment, known collectively as DATA Terminal Equipment or DTEs, and other communications equipment such as instruments, modems, and printers, known collectively as DATA Communications Equipment or DCEs. The RS232 Standard is the oldest and most widely used data interface standard for connections between DTEs and DCEs.
Typically, a DTE device is connected to a DCE device or another DTE device by means of a cable having as many as twenty-five signal lines which carry both data signals and control signals such as test signals and timing control information. Although the EIA Standard for connecting a cable to an RS232 interface is the most widely accepted cable configuration, it may not always be fully implemented or adhered to. With the increase of computing networks, DTE to DTE interfaces, and intelligent modems and printers, installation of an RS232 cable which has been properly configured for the particular installation has become a major concern. It would be desirable to provide a device or circuit which automatically configures the interface ports of an improperly configured interface cable to permit its use.